#define _CRT_SECURE_NO_WARNINGS 1
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
const int N = 30;
ll a[N][N];
int n, m, x, y;

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	cin >> n >> m >> x >> y;
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			a[i][j] = 1;
		}
	}
	a[x][y] = 0;
	if (x - 1 >= 0 && y - 2 >= 0) a[x - 1][y - 2] = 0;
	if (x - 2 >= 0 && y - 1 >= 0) a[x - 2][y - 1] = 0;
	if (x - 2 >= 0 && y + 1 <= m) a[x - 2][y + 1] = 0;
	if (x - 1 >= 0 && y + 2 <= m) a[x - 1][y + 2] = 0;
	if (x + 1 <= n && y - 2 >= 0) a[x + 1][y - 2] = 0;
	if (x + 2 <= n && y - 1 >= 0) a[x + 2][y - 1] = 0;
	if (x + 1 <= n && y + 2 <= m) a[x + 1][y + 2] = 0;
	if (x + 2 <= n && y + 1 <= m) a[x + 2][y + 1] = 0;

	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			if (i == 0 && j == 0) continue;
			if (a[i][j] == 0) continue;
			if (i == 0) {
				a[i][j] = a[i][j - 1];
			}else if(j==0){
				a[i][j] = a[i - 1][j];
			}else {
				a[i][j] = a[i - 1][j] + a[i][j - 1];
			}
		}
	}
	cout << a[n][m] << endl;
	return 0;
}